DNS of Separated Low-Re Flow Around a Cambered Aerofoil

Abstract

Recent improvements in manufacturing and control technology have led to the introduction of a new class of micro and even nano sized air vehicles (Micro/Nano UAVs) operating in flight conditions characterized by a medium-to-low Reynolds number and by background flow unsteadiness that may lead to critical aerodynamic conditions such as massive separation, dynamic stall and aerodynamic hysteresis. Although the effect of low Reynolds number regimes and its impact on boundary layer separation and flow unsteadiness have been the subject of many previous studies, fully stalled conditions did not receive much attention in the past. Using Direct Numerical Simulation, the present contribution addresses the spatio-temporal characterisation of the flow around a cambered aerofoil in deeply stalled conditions. A joint analysis of the flow structure and of the velocity time signal sampled in different locations allows to highlight the presence of a number of unsteady features that govern the overall behaviour of the flow field.

Notes

Acknowledgements

The authors gratefully acknowledge the support of the Engineering and Physical Sciences Research Council under the project Quiet Aerofoils of the Next Generation (EP/N020413/1) and ARCHER, the UK high-performance computing facility.